From: Senthil Kumar Selvaraj <senthilkumar.selvaraj@microchip.com>
Date: Mon, 17 Dec 2018 10:50:54 +0000 (+0000)
Subject: re PR rtl-optimization/88253 (Inlining of function incorrectly deletes volatile regis... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d7c00826362598d636ef1eb92a1b194d46b41473;p=gcc.git

re PR rtl-optimization/88253 (Inlining of function incorrectly deletes volatile register access when using XOR in avr-gcc)

Fix PR 88253

gcc/ChangeLog:

	PR rtl-optimization/88253
	* combine.c (combine_simplify_rtx): Test for side-effects before
	substituting by zero.

gcc/testsuite/ChangeLog:

	PR rtl-optimization/88253
	* gcc.target/avr/pr88253.c: New test.

From-SVN: r267198
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 83900c5b674..e63c4c9b50b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>
+
+	PR rtl-optimization/88253
+	* combine.c (combine_simplify_rtx): Test for side-effects before
+	substituting by zero.
+
 2018-12-17  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* doc/invoke.texi (-fversion-loops-for-strides): Document
diff --git a/gcc/combine.c b/gcc/combine.c
index 7e611399f2c..220c3a45631 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -5978,8 +5978,9 @@ combine_simplify_rtx (rtx x, machine_mode op0_mode, int in_dest,
 	    && known_eq (subreg_lowpart_offset (int_mode, int_op0_mode),
 			 SUBREG_BYTE (x))
 	    && HWI_COMPUTABLE_MODE_P (int_op0_mode)
-	    && (nonzero_bits (SUBREG_REG (x), int_op0_mode)
-		& GET_MODE_MASK (int_mode)) == 0)
+	    && ((nonzero_bits (SUBREG_REG (x), int_op0_mode)
+		 & GET_MODE_MASK (int_mode)) == 0)
+	    && !side_effects_p (SUBREG_REG (x)))
 	  return CONST0_RTX (int_mode);
       }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6fc2f0c9e5a..8ba858b5177 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>
+
+	PR rtl-optimization/88253
+	* gcc.target/avr/pr88253.c: New test.
+
 2018-12-17  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* gcc.dg/loop-versioning-1.c: New test.
diff --git a/gcc/testsuite/gcc.target/avr/pr88253.c b/gcc/testsuite/gcc.target/avr/pr88253.c
new file mode 100644
index 00000000000..7fa7e4efc69
--- /dev/null
+++ b/gcc/testsuite/gcc.target/avr/pr88253.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-Os -w" } */
+ 
+static int aRead() __attribute__((always_inline));
+static int aRead() {
+    unsigned char h,l;
+    l = (*(volatile unsigned char *)(0x78)) ;
+    h = (*(volatile unsigned char *)(0x79)) ;
+    return (h<<8) | l;
+}
+ 
+int main() {
+    volatile unsigned char x;
+     x = aRead()^42;
+ }
+ /* { dg-final { scan-assembler "lds r\\d+,121" } } */